An image reading device is used in devices such as a fax machine, a copier, and a financial terminal, and the image reading device performs duplicating of original copies, distinguishing authenticity of paper items, and distinguishing degree of circulation-induced wear. In order to irradiate a reading target object with light, the image reading device includes a light guide body that transmits light that enters the light guide body from a light source element.
The image reading device disclosed in Patent Literature 1 includes a linear light source device. The linear light source device includes a columnar plastic light guide body and a light source element that emits light to the light guide body. A band region is formed in a portion of a circumference surface of the light guide body, and recessed sections or protruding sections are formed extending linearly in the width direction of the band region. Light entering from an end portion of the light guide body is emitted from a region opposite to the band region.
A lighting device including a light guide body is disclosed in Patent Literature 2. In a portion of a circumferential surface of the light guide body, a light scattering member is formed by attaching of a film, printing of a coating, and the like. The light entering the light guide body from a light guide body end portion is emitted from a region opposite to a light scattering portion.
The light guide body disclosed in Patent Literatures 3 and 4 includes a reflection surface in which are formed light reflection members. The light reflection member is formed with a semi-ellipse shape projecting in an emission plane of the light guide body. Shape of the light reflection member varies with the position of arrangement in a main scanning direction.